Quick check of toilet drain connection before I pour concrete?

Sorry if this is considered a double post - I had posted this in another thread, but didn't get a confirmation that my configuration is ok. I'm just about ready to pour concrete and want to make sure I'm not making a mistake.

Can someone please have a look at how I connected the toilet and shower drain to my sewer pipe and let me know if this is ok? I'm not sure if the use of a sanitary tee is ok or not. I couldn't find a way to use a wye and still get my closet flange where it needs to be.

I wasn't really comfortable with the T-Y either, but I couldn't fit a wye unless I did away with the backflow valve.

I pulled up the carpet in another room and uncovered a mysterious sump that I haven't opened since I bought the house. I opened it up and low and behold there was a backflow valve installed after all.

I pulled the other backflow valve that I previously installed and used a 45 elbow and a wye to connect the toilet and shower drain. I presume this is a better solution. I'm more comfortable covering it up now, but if there is still something wrong here, please let me know ASAP.

I would be willing to bet that any backwater valve that old is almost completely non-functional by now. The toilet connection looks okay, but we cannot tell what your other piping is like, since that COULD affect whether it is done right or not. What is the white "bulbous" thing on the 2" line and is it connected to the 3" one with a backwards "Y"?

I would be willing to bet that any backwater valve that old is almost completely non-functional by now. The toilet connection looks okay, but we cannot tell what your other piping is like, since that COULD affect whether it is done right or not. What is the white "bulbous" thing on the 2" line and is it connected to the 3" one with a backwards "Y"?

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I pulled the cover off the backflow valve. The flap opens and closes freely and the seal and closing surface seems to be in decent shape. It's easily accessible now that I know where it is so I can always swap it out later if need be.

The ABS pipe with the PVC elbows on it is just a perferated 3" drain tile that runs under my slab. I couldn't find any ABS fittings that would fit this pipe, and they are not glued anyway so I didn't figure it would be a problem.

If it is "undersized" SDR pipe, then it is PVC, regardless of the color, because they never made ABS pipe that thin.

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I guess it must be black PVC then because it is a lot thinner walled than 3" ABS. One less thing to be concerned about then. I think I'm ok now, so time to pour the concrete. Thanks for the pointers guys.